First bike, carb work, need help; '80 GS450, maybe '82 GS450T

[Meximus]

So, whoever had this bike before me was an idiot. When I bought the bike it was idling around 5000rpm, which is a pretty common problem. To start off, there are no vacuum leaks that I have been able to find.

What I did find was that the fuel/air screws were offset by about a turn. Right was set too lean. Fixed it to factory spec.

Spark plugs were gapped completely different; right side was almost touching the contact and the left was waaay open. Bought new plugs.

Ignition coil on right side is cracked and leaking, reading some 28k ohms in the secondary. Replaced coil.

Diaphragm slide springs were completely different; different weights, daimeter, rate of turns, & length. Replaced springs.

Now I find that one of the needles dangles out of the slide/diaphragm assembly. The other one has spring tension on it when I gently pull. Unfortunately, the good needle also appears to be scored. It has black marks all down one side, as though it were making contact with something inside the carb body. That same one also had a tab missing from what I guess is the needle retainer plate. I can look through it like a peephole.

Need some advice on how to proceed. Should I just go buy another carb and start canabing parts or are there assemblies that will work with my bike.

Oh, and that's the fun part. The dude sold it to me as a 1980 GS450. Couldn't get a hit when I ran either the VIN on the motor or the frame; which are different. The plastic guard that covers the electrical crap says GS450T, which would make it an '82.

Note: I can only upload one photo so I combined the three I took. You can see how much farther down the loose one dangles as well as the black scoring on the "good" needle and the broken retaining thing.

 

[tom203]

Of course you got this bike cheap! Carbs seem butchered- I'd look for a ebay set and save myself grief. But only if rest of bike is worth it.
I liked your 3 in 1 pic. Go here and read how to post pics

http://members.dslextreme.com/users/bikecliff/images/how_to_post_pictures.pdf

 

[Steve]

I am going to comment within your quote:

So, whoever had this bike before me was an idiot. When I bought the bike it was idling around 5000rpm, which is a pretty common problem. To start off, there are no vacuum leaks that I have been able to find.
Not sure what mechanic's school you went to, but 5000 RPM is NOT "idling".

What I did find was that the fuel/air screws were offset by about a turn. Right was set too lean. Fixed it to factory spec.
How did you find "factory spec"? The screws were set by a machine at the factory, then sealed. Each carb was just a little bit different, nobody really knows what the setting used to be when it left the factory. And, due to wear and tear through the years, it is not unusual for the settings to be different. You have to tune each carb individually.

Spark plugs were gapped completely different; right side was almost touching the contact and the left was waaay open. Bought new plugs.
Probably a good move. Did you check the gap on the new plugs? Even new plugs don't necessarily come with the proper gap.

Ignition coil on right side is cracked and leaking, reading some 28k ohms in the secondary. Replaced coil.
Probably a good move.

Diaphragm slide springs were completely different; different weights, daimeter, rate of turns, & length. Replaced springs.
Probably a good move.

Now I find that one of the needles dangles out of the slide/diaphragm assembly. The other one has spring tension on it when I gently pull.
Having spring tension is proper.

Unfortunately, the good needle also appears to be scored. It has black marks all down one side, as though it were making contact with something inside the carb body.
Not unusual to see some drag marks on a needle from a high-mileage engine, but that is not what is shown in your picture.

That same one also had a tab missing from what I guess is the needle retainer plate. I can look through it like a peephole.
Sounds like you need the needle retainer plate. Probably also the nylon spacer that sits over the clip on the needle and the circlip that holds the retainer plate in place.

Need some advice on how to proceed. Should I just go buy another carb and start canabing parts or are there assemblies that will work with my bike.
You will be hard-pressed to get a NEW carb, you will have to find one used, or see if anyone here has some spare parts. I might have what you need.

Oh, and that's the fun part. The dude sold it to me as a 1980 GS450. Couldn't get a hit when I ran either the VIN on the motor or the frame; which are different.
Don't worry about the non-matching numbers. NONE of the engine numbers EVER matched the frame numbers.

The plastic guard that covers the electrical crap says GS450T, which would make it an '82.
Not sure what plastic guard or what electrical crap you are talking about, but the VIN plate on the steering stem is your definitive identifier. You have to be careful with the letters after the engine size. There is one that is not always visible and not everybody knows about it, but it shows the model year. The letter "T" is actually for the 1980 model year, so if you have a 1980 GS450E, it is actually a GS450ET. (Saying "1980" and the "T" is redundant.) Keep in mind that there was also a GS450T. If it was a 1981 450T, it would be a GS450TX. If it were an '82 model, it would be a GS450TZ. The VIN plate will show you that, the side covers will not.

Note: I can only upload one photo so I combined the three I took. You can see how much farther down the loose one dangles as well as the black scoring on the "good" needle and the broken retaining thing.

View attachment 50560

 

[JTGS850GL]

Looking at the pictures it looks like the needles are different as well. Time to bite the bullet and learn how to rebuild the carbs.

Here's a tutorial that will help.: http://zeus.mtsac.edu/~cliff/storage/gs/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf

Look at the link at the bottom of my signature. It will provide you with a ton of information.

 

[Gorminrider]

Couldn't get a hit when I ran either the VIN on the motor or the frame

. They never match on these bikes. You can tell what year it is from VIN maybe from frame if you have no VIN.

So....taken from some of the stuff I scoop from the web, if it's a 1980 it might have a frame number like "500xxx" which is 450 ET, "600xxx" which is 450 ST (E with a fairing) "700xxx" is 450LT Not sure what a TT would be in this... . Someone else might confirm this?

But starting 1981 it should have a real VIN and these are well understood. "JS1GLxxxxxxxxxxxx"" the tenth character ( B,C,D, etc.. ) is year. '81 being "B".

The engines and carbs are pretty much the same throughout the models and for several years BUT get the manual AND have a look at a parts fiche. I use this one but theres some info on Bass-cliffs per cross relating part numbers at a different site....parts suzuki motorcycle accessories spares replacement aftermarket
yes in your case some 450 carbs are worth getting .

 

[Meximus]

. They never match on these bikes. You can tell what year it is from VIN maybe from frame if you have no VIN.

So....taken from some of the stuff I scoop from the web, if it's a 1980 it might have a frame number like "500xxx" which is 450 ET, "600xxx" which is 450 ST (E with a fairing) "700xxx" is 450LT Not sure what a TT would be in this... . Someone else might confirm this?

I got to poking around in it and I found a label plate that said it was mfg in 10/79. It's one of the 500xxx numbers.

That website is exactly what I have been looking for. Thank you so much!

 

[Meximus]

Looking at the pictures it looks like the needles are different as well. Time to bite the bullet and learn how to rebuild the carbs.

The needles are identical, as far as I can tell; one just hangs down lower because there is no spring tension on it. The other is scored black; I can only assume from contacting something inside the carb body. I wasn't sure so I was seeing what you guys thought.

Thanks, for the link, btw. Finding that page is one of the reasons I decided to get this bike in the first place. There seemed to be a lot of information and knowledgeable people to help with the project. Planning on building a scrambler once I get it working right; which is why I didn't mind the fact it needed work to begin with.

 

[Meximus]

By "idling" I mean a state in which the engine is running and no throttle is being applied. When the bike was in that state it's RPMs read 5000, as opposed to the spec of 1100-1300RPM that is is supposed to be at. Also, if I had gone to mechanic's school I wouldn't be on the internet asking strangers for help. As the post says, this is by first motorcycle. I don't need, nor do I want, attitude about my experience level; it's a Franken450 that had an incompetent mechanic and I am trying to fix it. Hell, he tried to secure the hoses with zip-ties instead of hose clamps!

Every resource I found said the screws should be adjusted approximately 2 turns up from shut. My carbs were not sealed; not to mention parts that didn't match it to begin with so I was trying to get a baseline to start from.

I also am well aware that I can't get a "new" carb, but I can buy a rebuilt one for about $300 on ebay. I would prefer to replace the broken and missing parts I have which is why I am posting this to begin with.

The nylon retainer is what is broken, but the circle clip is intact as far as I can tell. I didn't want to disassemble that part until I got a better idea of what I was breaking into. I found blow-ups online, but I needed advice on where to get parts and what parts to get as simply Googling it brought up nothing. I did find a cheap Mikuni BS34, 4-body, that should be shipping to me soon that I plan to rip apart for spare parts: 4 bodies for $40, most seem intact, figured it was a good deal.

As far as the plastic guard that covers the electronics; every GS450 has them so I figured someone would know what I was talking about:

 

[sam000lee]

There is a bag of tiny washers you can get at radio shack for around $2.50 that you can replace the little plastic needle spacer with (3 is closest to factory height IIRC). They go on top of the needle clip. There are tons of washers of sizes that you won't use but there are plenty of the ones that fit around the needle.

As far as carbs not being sealed - it's likely that a PO took the pressing out covering the mixture screw.